The present invention relates to a transmission joint of the type comprising a first and a second rotary member, a boot connected by a front end region to the first rotary member and by a rear end region to the second rotary member, and means for axially retaining the rear end region of the boot with respect to the second rotary member which comprise a retaining enlargement and a groove for housing the retaining enlargement, the rear end region of the boot and the second rotary member having matching transverse outlines of which the directrix curves exhibit points of inflection.
The invention applies in particular to tripot constant-velocity transmission joints.
Such joints allow a rotary movement to be transmitted between a first shaft bearing a male element or tripod and a female element or bell housing which rotates as one with, for example, the output side gear of a differential.
The tripod has three arms each bearing a rolling assembly. Each rolling assembly is intended to roll on a pair of tracks formed in the bell housing. The tripod and the bell housing have ternary symmetry.
The rear end region of the boot is slipped over a front end region of the bell housing.
The bell housing is produced in particular by forging and, in cross section, has, in alternation, convex parts and concave or flat parts. The terms xe2x80x9cconvexxe2x80x9d and xe2x80x9cconcavexe2x80x9d are to be understood as meaning with respect to the outside of the bell housing. The convex parts are farther from the longitudinal axis of the bell housing than the concave or flat parts.
The groove that houses the retaining enlargement is therefore made in each of the convex parts from the radially outer surface of the bell housing. The retaining groove therefore extends discontinuously around the periphery of the bell housing.
The enlargement extends peripherally in a corresponding way on the radially inner surface of the boot.
A clamping member clamps the rear end region of the boot onto the front end region of the bell housing, holding the retaining enlargement inside the housing groove.
The housing groove is generally formed in the bell housing by turning. Because of the discontinuous nature of the groove, such a machining operation poses numerous problems including relatively high wear of the cutting tool used, and the difficulty of producing a groove whose various portions are concentric.
Furthermore, the number of portions of the housing groove and their angular extent depends on the number of convex parts of the bell housing and on their angular extent.
Thus, the total angular extent of the retaining housing groove may be relatively small and the axial retention of the rear end of the boot with respect to the bell housing may therefore not be satisfactory.
The object of the invention is to solve these problems by providing a transmission joint of the aforementioned type that makes it possible to limit the difficulties of machining the bell housing and to increase the angular extent of the groove that houses the retaining enlargement for a given transverse profile of bell housing.
To this end, the subject of the invention is a transmission joint of the aforementioned type, characterized in that the enlargement is situated on the periphery of the second rotary member and spaced axially from the front end of the second rotary member and in that the groove is formed on the periphery of the boot.
According to particular embodiments, the transmission joint may include one or more of the following features, taken in isolation or in any technically feasible combination:
the retaining enlargement and the groove that houses the retaining enlargement have roughly matching longitudinal profiles,
the retaining enlargement extends discontinuously around the periphery of the second rotary member,
the retaining enlargement comprises several portions spaced roughly regularly about the periphery of the second rotary member,
the groove that houses the retaining enlargement extends around the periphery of the boot in a similar way to the retaining enlargement around the periphery of the second rotary member,
the boot comprises sealing means located axially on the same side with respect to at least part of the groove that houses the retaining enlargement,
the sealing means are located axially on the same side with respect to the entirety of the groove that houses the retaining enlargement,
the sealing means are located axially to the rear of said part of or the entirety of the groove that houses the retaining enlargement,
the sealing means are located radially on the same side of the boot as the housing groove,
it comprises a member for clamping the rear end of the boot onto the second rotary member,
the clamping member is located axially, with respect to at least part of the groove that houses the retaining enlargement, on the same side as the boot sealing means,
the retaining enlargement is situated on a radially outer surface of the second rotary member and in that the housing groove is formed on a radially inner surface of the boot,
the retaining enlargement is formed on the second rotary member by upsetting the material of the second rotary member.